Dynamic proportional metering device for fluids

ABSTRACT

This dynamic proportional metering device for fluids comprises a time-lag unit and a capacity of which the filling time is a linear function of the main fluid output, a pressure pulse generator delivering pulses at a frequency proportional to said filling time and a function of the main fluid output, a pulse regulator, a pulse pump for displacing a volume of intermediate fluid acting upon a compression chamber co-acting with a secondary-fluid injection unit; this metering device is particularly suited for injecting an odorous fluid into a stream of natural gas.

United States Patent [191 Castan et al.

DYNAMIC PROPORTIONAL METERING DEVICE FOR FLUIDS Inventors: JosephCastan; Claude Francis Fernand Yves Fremont, both of Levallois, FranceHERFILCO, Levallois (l-lauts de Seine), France Filed: Aug. 21, 1973Appl. No.: 390,259

Assignee:

Foreign Application Priority Data Sept 26, 1972 France 72.34059 US. Cl222/57, 137/564.5, 222/193 Int. Cl B67d 5/18 Field of Search 137/10l.1l,564.5; 222/52,

References Cited UNITED STATES PATENTS Cassese 137/5645 X Aug. -'20,1974 3,200,840 8/1965 Watts ..137/564.5 3,283,957 11/1966 Henderson222/57 Primary Examiner-Allen N. Knowles Assistant ExaminerLarry H,Martin Attorney, Agent, or Firm-Fleit, Gipple & Jacobson This dynamicproportional metering device for fluids comprises a time-lag unit and acapacity of which the filling time is a linear function of the mainfluid output, a pressure pulse generator delivering pulses at afrequency proportional to said filling time and a function of the mainfluid output, a pulse regulator, a pulse pump for displacing a volume ofintermediate fluid acting upon a compression chamber co-acting .with asecondary-fluid injection unit; this metering device is particularlysuited for injecting an odorous fluid into a stream of natural gas.

ABSTRACT 4 Claims, 4 Drawing Figures PATENIED 141112201914 SHEET 10$ 3 IDYNAMIC PROPORTIONAL METERING DEVICE FOR FLUIDS The present inventionrelates to dynamic proportional metering devices for fluids and isdirected to an improved device of .this character intended moreparticularly but not exclusively for injecting a liquid odorous fluidinto a natural gas. Another possible application of this device may bethe mixing of several ingredients in proportions determined withprecision.

When it is desired to meter a secondary fluid proportionally to a mainfluid output, two types of methods may be adhered to, basically.

The so-called static methods utilize mixing chambers. In these methods,one fraction of the main fluid is saturated by tapping or by-passingwith the secondary fluid put into direct contact therewith, the mixturebeing subsequently reinjected into the main duct of conduit. By properlyselecting the diameters of the various pipe lines, a certainproportionality is actually obtained, but this proportionality israpidly modified even by very moderate temperature variations.

The so-called dynamic methods such as those carried out inservo-controlled metering pumps require the use of a counter deliveringan electric signal utilized for varying the output of a mechanical pump.

It is an essential object of the present invention to provide a devicecapable of metering and possibly injecting a secondary fluid inproportion to the output of a main fluid while combining the advantagesfeatures of the two known types of methods mentioned hereinabove andeliminating their inconveniences.

The device according to this invention may be rendered on the one handcompletely self-operating by deriving the power necessary for itsoperation from the main fluid stream, and on the other hand fluid-tightby re-injecting any leakage fluid into this stream.

The present invention is based on the following principle: a tankcontaining the main fluid is emptied into a header through a conduitenclosing a vacuum generating member, for example a diaphragm. On theother hand, a metering member picks up secondary fluid from a tank forinjecting this secondary fluid into another downstream header with anoutput proportional to that obtaining in the conduit connecting thefirst or main-fluid tank to the first header. Any leakage may berecovered in the header which may also provide the necessary auxiliarydriving counterpressure; thus, a self-operating and fluid-tightapparatus isobtained. The two headers may be separate headers or mergedinto one.

According to this invention, in an arrangement of the type disclosedhereinabove the dynamic proportional metering device for the secondaryfluid is characterised in that it comprises a time-lag device consistingof a proportional output regulator and a capacity of which the fillingtime is a linear function of the main fluid output; a pulse generatorconsisting of a plurality of pistons generating a pressure pulsefrequency proportional to the filling time of said time-lag capacity anda linear function of the main fluid output; a pulse regulator consistingof a capacity connected to said pulse generator, to a pump and to thedownstream side of the expansion; a pulse pump for injecting a volume ofintermediate fluid acting on a compression chamber coacting with asecondary fluid injection unit; said metering device being furthercharacterised in that it comprises, in addition to said dynamic members,three static members, namely a filter" for the driving fluid, asecondary fluid filter and a reservoir for containing the oil or anyother suitable intermediate liquid fluid.

Other features and advantages of this invention will appear as thefollowing description proceeds with reference to the attached drawingsillustrating diagrammatically by way of example a typical form ofembodiment of the invention. In the drawings:

FIG. 1 is a general diagram of the metering device of this invention;

FIG. 2 is a sectional viewof the time-lag device;

FIG. 3 is another sectional view showing the pressure pulse generator,and

FIG. 4 is a further section showing the pulse pump and the injectionunit.

Refering first to FIG. 1 showing in a dash-and-dot line frame 1 thegeneral arrangement of the metering device of this invention, a mainconduit section 2 in which the main fluid can flow in the directionshown by the arrow F, has fitted therein a vacuum generating member 3such as a diaphragm.

The metering device comprises a driving-fluid filter 4 for cleaning thedriving fluid, which is followed by a time-lag device 5 with theinterposition of a proportioning device R (the information taken fromthe diaphragm may be replaced by any suitable pressure information or aninformation representing the differential pressure between two points,which may possibly lead to the limitation of R a pressure pulsegenerator 6, a pressure pulse regulator 7, followed by a pulse pump 8and a secondary fluid injection unit 9 to which a secondary fluid F isdelivered through a secondary fluid filter 10; an oil reservoir 11 for apurpose to be explained presently, being also provided.

The structure and mode of operation of each one of the abovelistedmembers and units will now be explained in detail.

FIG. 2 illustrates the structure .of the time-lag device 5 comprisingessentially a proportional output regulator l2 and a capacity or chamber13. By adjusting this regulator 12 the capacity 13 can be filled more orless rapidly so as to render the filling time T of this capacity alinear function of the main output Q. The derivated' output q flowingthrough this regulator 12 is obtained by virtue of the vacuum-generator3 fitted in the main conduit 2.

The time-lag device 5 operates as follows: when no fluid output isproduced in the main conduit, the movable assembly of regulator 12 (i.e.diaphragm 14, plate 15, seat 16) is inoperative and closes the feednozzle 17 leadingto chamber 13. When an output is circulating in saidmain fluid conduit, a want of balance occurs in the pressures on eitherside of the diaphragm 3 (with upstream pressure I greater thandownstream pressure P',) and also of the movable assembly of regulator12, thus opening the feed nozzle 17.

If the output Q increases, P decreases, the nozzle opening increases,and vice-versa. The variation of P, is rendered proportional to theoutput Q due to the presence of R whereby the displacement of themovable assembly and the filling time T of chamber 13 are proportionalto Q. Therefore, the time-lag device causes T to be equal to f (O).

The chamber 13 opens into the pressure pulse generator 6 (FIG. 3)comprising three pistons l8, l9 and 20, of which pistons 19 and 20 aremovable, piston 18 being stationary and adjustable, and a pair of returnsprings Rsl, R52 associated with pistons 20 and 19, respectively. Adifferential non-return valve 21 permits an integral flow in onedirection and a reduced flow in the opposite direction.

The pressure pulse generator 6 operates as follows: the pressure Pincreasing in time-lag device 5 forces the piston 19 upwards thuspushing the next piston 20, whereby return springs Rsl and Rs2 arecompressed. Therefore, three actions take place simultaneously;

i. Since pressures P and P differs, with P, P (P being the pressure involume V above piston 20), pistons l9 and 20 move upwards, the fluidtightness between these pistons being ensured by concentric 0- rings aand b.

ii. The volume V compressed by piston 20 escapes downwards through thedifferential non-return valve (full flow).

iii. Since piston 18 is fixed, it determines the stroke of pistons 19and 20, the stroke limit being the elimination of the fluid-tightness ofO-ring c.

When this O-ring c is no more tight, a pressure balance is created onpiston 19, between O-rings a and b, and since this piston is no moreexposed to the differential pressure (P P it is urged by spring RS2 andquickly resumes its initial position.

Piston 20 is urged by spring Rsl and its movement is attended by asuction in chamber V, this suction being retarded by the differentialnon-return valve 21 (restricted flow) so that the return movement ofpiston 20 g The frequency of the pressure pulses generated by the device6 is subordinate to the filling time T of chamber 13 of time-lag device5, and also to the return speed of piston 19. This frequency is thusmade proportional to the output Q by the differential non-return valve.The pulse generator 6 will thus provide a pulse frequency F proportionalto T and this frequency is a linear function of Q.

The pulse regulator 7 following the generator 6 comprises a capacityconnected to the generator, to a pulse pump 8 and to the downstream endof an expansion line 31. The exhaust in the downstream direction takesplace through cock R2. The compressed volume escaping suddenly from thepulse generator causes a sudden pressure increment in the regulator. Theexhaust output in the downstream direction is retarded by the cock R2,so that the pressure can be maintained during a time sufficient toactuate the pump 8.

Referring to FIG. 4 illustrating the pump 8 and the secondary-fluidinjection unit inserted in the main conduit, it will be seen that thispump 8 comprises a diaphragm piston 22, a return spring R33, a strokeadjustment member 23, a pressure-building piston 24 rigid with saiddiaphragm piston, and an oil supply, this oil constituting theabove-mentioned intermediate fluid.

The pump 8 operates as follows: the sudden pressure rise in regulator 7actuates the diaphragm piston 22 which compresses the return springR931. The pressurebuilding piston is thus moved and traps a certainvolume of oil so as to drive same. Thus, the amount of secondary fluidinjected into the main fluid stream is sub- 4. ordinate to this oilvolume driven by the pressurebuilding piston.

The injection unit comprises an assembly of nonretum inlet valves 25, anassembly of exhaust valves 26, a compression chamber 27 and a tube 28 ofpolytctrafluoroethylene or any other suitable deformable materialconnecting said inlet valves to said exhaust valves. The compressionchamber 27 surrounds the deformable tube 28 and is filled with oil.

This unit operates as follows: the volume of oil trapped as aconsequence of the movement of piston 24 and subsequently compressed incompression chamber 27 causes the tube 28 to undergo a deformation so asto compress the volume of secondary fluid contained between the inletvalves 25 and exhaust valves 26. This compression opens the exhaustvalves and the secondary fluid contained in tube 28 is forced out andinand exhaust valves for the secondary fluid F in tube This principle ofoperation of a pulse pump and injection unit assembly permits ofmetering very small amounts of secondary fluid isolated in tube 28, thuseliminating the risk of piston corrosion and also of contamination dueto leakage through the unions and gland packings. Finally, it will beseen that the oil reserve of the injection unit is connected to thedownstream end of the expansion side so that, when the assembly isinoperative, a zero differential pressure is obtained in tube 28.

The metering device according to this invention is operable with allfluids and capable of supplying very low secondary fluid outputs, oralternatively very high secondary fluid outputs, according to the pistondiameter.

Moreover, a pulse counter may be implemented for totalizing thequantities of main and secondary fluids.

When the main-fluid and secondary fluid tanks are at the same pressure,the apparatus may be simplified by producing a continuous meteringaction just after the regulator 12, the main fluid being fed to theone-port chamber while the secondary fluid is fed to the twoportchamber.

Although a specific form of embodiment of this invention has beendescribed hereinabove and illustrated in the accompanying drawing, itwill readily occur to those skilled in the art that variousmodifications and changes may be brought thereto without departing fromthe scope of the invention as set forth in the appended claims.

We claim:

1. A proportional metering device for fluids, characterized in that itcomprises a time-lag unit connected to a main conduit said time-lag unitcomprising a proportional output regulator and a capacity of which thetilling time is a linear function of the main fluid output through saidconduit; a pulse generator connected to said time lag-unit, said pulsegenerator comprising a plurality of pistons which generate a pressurepulse frequency proportional to the filling of said capacity of thetime-lag unit and a linear function of the main fluid output; a pulseregulator consisting of a capacity connected to said pulse generator, toa pulse pump, and to a downstream end of an expansion line; said pulsepump having means for displacing a volume of intermediate fluid into asecondary fluid injection unit; said secondary fluid injection unitconsisting of a deformable tube within a compression chamber thatco-acts with the intermediate fluid for dispensing a metered amount ofsecondary fluid into said main conduit; the proportional metering devicefurther including a driving fluid filter connected between said mainconduit and said time-lag unit, a secondary fluid filter connected tosaid injection unit and an oil reservoir for storing said intermediatefluid.

2. Metering device according to claim 1, characterised in that saidproportional regulator of said time-lag device consists of a diaphragmvalve that closes in the absence of the main fluid output and opensproportionally to the main fluid output for filling said time-lag devicecapacity.

3. Metering device according to claim 1, characterised in that saidpressure pulse generator pistons that compress a volume under the actionof said time-lag device and create a pulse frequency that is applied tosaid pulse regulator which is proportional to the filling time of saidtime lag device capacity and a linear function of the main fluid output.

4. Metering device according to claim 1, characterised in that saiddeformable tube has at one end, inlet non-return valves for thesecondary fluid and at the other end exhaust non-return valves for thesecondary fluid, the oil filling said compression chamber being drivenby the pulse pump which means for displacing the volume of intermediatefluid comprises a pistons which is responsive to the pressure pulseaction of said pressure regulator.

1. A proportional metering device for fluids, characterized in that itcomprises a time-lag unit connected to a main conduit said time-lag unitcomprising a proportional output regulator and a capacity of which thefilling time is a linear function of the main fluid output through saidconduit; a pulse generator connected to said time lag-unit, said pulsegenerator comprising a plurality of pistons which generate a pressurepulse frequency proportional to the filling of said capacity of thetime-lag unit and a linear function of the main fluid output; a pulseregulator consisting of a capacity connected to said pulse generator, toa pulse pump, and to a downstream end of an expansion line; said pulsepump having means for displacing a volume of intermediate fluid into asecondary fluid injection unit; said secondary fluid injection unitconsisting of a deformable tube within a compression chamber thatco-acts with the intermediate fluid for dispensing a metered amount ofsecondary fluid into said main conduit; the proportional metering devicefurther including a driving fluid filter connected between said mainconduit and said time-lag unit, a secondary fluid filter connected tosaid injection unit and an oil reservoir for storing said intermediatefluid.
 2. Metering device according to claim 1, characterised in thatsaid proportional regulator of said time-lag device consists of adiaphragm valve that closes in the absence of the main fluid output andopens proportionally to the main fluid output for filling said time-lagdevice capacity.
 3. Metering device according to claim 1, characterisedin that said pressure pulse generator pistons that compress a volumeunder the action of said time-lag device and create a pulse frequencythat is applied to said pulse regulator which is proportional to thefilling time of said time-lag device capacity and a linear function ofthe main fluid output.
 4. Metering device accordiNg to claim 1,characterised in that said deformable tube has at one end, inletnon-return valves for the secondary fluid and at the other end exhaustnon-return valves for the secondary fluid, the oil filling saidcompression chamber being driven by the pulse pump which means fordisplacing the volume of intermediate fluid comprises a pistons which isresponsive to the pressure pulse action of said pressure regulator.